MONDAY, Nov. 25, 2013 (HealthDay News) -- A new vaccine has been approved by the U.S. Food and Drug Administration to prevent the so-called "bird flu" virus in adults at greater-than-average risk of exposure, the FDA said.

While most strains of bird flu don't infect people, the H5N1 virus has caused "serious illness and death in people outside of the U.S., mostly among people who have been in close contact with infected and ill poultry," the agency said in a news release announcing the approval.

The shot, called the Influenza A (H5N1) Virus Monovalent Vaccine, has been developed "in the event that the H5N1 avian influenza virus develops the capability to spread efficiently from human to human, resulting in the rapid spread of the disease across the globe," the FDA added.

The vaccine, produced by a Canadian subsidiary of GlaxoSmithKline, is not intended for commercial distribution, the FDA said. It's designed to be administered in two doses given three weeks apart.

In clinical testing involving some 3,400 adults, the most common side effects included injection-site pain and swelling, muscle aches, headache and fatigue.